Aerators are commonly used for maintaining landscaped ground surfaces including turf. The term “turf” refers to grass and other material which is specifically grown for sporting activities and is used, for example, to form golf course greens. Aerators on these types of surfaces have tines that repeatedly penetrate the ground surface, forming a plurality of holes so that the ground surface is aerated, to improve growth of the grass or other material and enhance the condition of the surface for playing purposes.
Aerators may have flywheels that drive the upper ends of tine supports in a circular path, and the lower ends in a reciprocating motion of repeated penetrations into the ground. Link arms can pivot to compensate for forward motion of the machine. At each part of the cycle when the tines are withdrawn from the ground surface, the link arms may position the tines in a substantially vertical position for the next cycle of penetration into the ground. Tines are generally cylindrical, are hollow or solid, and produce holes by pulling up plugs or cylindrical cores of soil as the tines move by rotation of the flywheel.
Walk-behind aerators typically have fixed hole spacing control positions. The hole spacing settings can be and typically are set between 0 and 6 inches. For example, the aerator may have a mechanical lever that can be used to select a mechanical stop, that in turn selects a gear in the transmission of the vehicle. Additionally, the hole spacing depends on the speed of the vehicle and the linkages between the engine and the coring head drive system.
For example, an operator may select a desired hole spacing, set the engine to full throttle, and then engage the coring head. The operator may need to adjust the throttle position until the hole spacing corresponds as close as possible to the selected setting. The mechanical drive system will move the aerator vehicle at a designated speed while rotating the coring head at a translated RPM, and thereby produce a pattern that approximates the selected spacing. The hole spacing may change, however, if the engine slows or speeds up, is not running smoothly, or if one or more transmission belts for the coring head drive system stretch and/or wear over time.
An aerator with a hole spacing control system is needed that can produce holes at the desired spacing regardless of the engine speed or other fluctuations in vehicle performance.